Point initiating fuse for shaped charge projectiles



March 1954 A. F. TEITSCHEID ETAL ,670,682

POINT INITIATING FUSE FOR SHAPED CHARGE PROJECTILES Filed Jan. 16. 1950 2 Sheets- Sheet l 2,] vwem fms Hlfred; E'Teikschied Donald R. E; eeman.

Hg'man llfiuikmvsky March '2, 1954 A. F. TEITSCHEID EIAL POINT INITIATINC FUSE: FOR SHAPED LCHARGE PROJECTILES Filed Jan. 16. 1950 2 Sheets-Sheet 2 Elf Teri RTE Hsnhiad Ilmnafcf R Eleemam H -nan DRuiKuvsKH Patented Mar. 2, 1954 POINT INITIATENG FOR SHAPED CHARGE PROJECTILES I Alfred F. Tcitscheid and Donald R. Beeman,

Whartonfand 1 Hyman D: Ruthovsky, Dover, N. J., assignors to the United States of America as represented by the Secretary of the Army Application January 16, 1950, Serial No. 138,871

4 Claims.

(Granted under Title 3 The invention described herein may be manufactured and usedby. or for the Government for governmental purposes without the payment of any royalty thereon;

This invention relates to high explosive antitank projectiles based upon-the shaped charge principle. Thev extremely effective armor-penetrating action-of the jet formed by detonation, under proper conditions, of a shaped charge, is well-known. Such-conditions involve principally the detonation of the'charge at the correct standoff distance from the-target, the shape of the cavity, and; a path of minimum obstruction between the cavity and target at the time of detonation. 1

Prior to the present invention, it was customary to detonate shaped-charge projectiles by means of fuzes located inthe base of the projectiles since initiation of the deonation must be at the baseof the charge. In anearly type of-fuze for this purpose, the base-detonating .fuze employed an inertia plunger which moved in response to impact to fire. the charge; -However, such plungers have an inherent-delay in operation and, sincethe timing oi the detonation of the charge is critical, a heavy ogival windshield was provided over the nose of the projectile in order to effectsufiici'ent retardation..-to assure functioning'of the fuze at the desired stand-off distance. Onthe'other hand; such a heavy windshield was undesirable in-tha-t it interfered with thepenetrating action of the jet. "It has been proposed to provide such a projectile with a shaped charge having a central linedaXial-passageway, together with a point-initiating fuze and an auxiliary detonator using a shaped charge" to direct a flame or detonating flash. rearwardly along the'passageway to thereby efiect the base detonation of the main charge. However, such fuzes' 'employed a firingpinior detonation and were therefore subject to at least some'of the drawbacks of the base-detonating type because 01" the inherent inertia of the firing pin and its obstruction and impairment of full jet action.

Furthermore; with the type fuze just mentioned, the .ogival windshield had to be heavier and-morerugged thanwould otherwise be necessary, in order to provide adequate attaching threads for the primer and to rigidly support it in position during loading.

It'is the principal object of our invention to;

provide a highly-efiicient point-initiating fuze for high explosive shaped charge. projectiles wherein the draw'backsof prior artfuzesasjust explained.

are lessened or eliminated. I

5, U. S. Code (1952), sec. 266) A further object is to provide a point-initiating fuzewhich is positive in action and which will detonat the associated shaped charge at-an ope timum substantially. constant stand-off distance from the target.

Another object is to provide a iuze of the type described which is carried wholly by the casing or body of the projectile and which thus requires only a thin light protective nose cap or windshield so that the latter is easily crushed and oiiers minimum obstruction to the ensuing jet from the shaped charge. l f y A still further object is to provide a pointinitiating fuze for use with a shaped charge, which has a safety device armed only in response to the centrifugal force engendered by the rota: tion of the projectile in firing.

Another object is to provide a fuze of the type mentioned whose metal frame can be made as a casting of light aluminum alloy, thus offering only slight obstruction to the jet.

Yet another object is to provide a fuze of the type described employing an auxiliary detonator operating upon the shaped charge principle wherein the detonator is-capable of initiatinga tetryl booster pellet in the base of the projectile, in contradistinction to the more sensitive exploq sives such as lead azide, formerly required in. such pellets.

Another object is to provide a fuze of the type mentioned wherein detonation is initiated by a sensitive primer carried independentlyof, but located closely adjacent the front end of the thinwalled ogival nose cap or windshield, wherebya firing pin and its attendant drawbacks, are eliminated. v

Still another object is the provision of a fuze threaded on the outside of the projectile whereby, on impact, maximum disintegration of the; fuze body is assured with a concomitant lessening'of obstruction to the ensuing jet and a maximum penetration of the target. Other objects and advantages will become apparent after-a study of the following specification in connection with the accompanying drawing wherein:

Figure 1 is a longitudinal axial section through the nose of a shaped charge projectile equipped with the improved point-initiating fuze in unarmed condition, Figure 2 is alongitudinal axial section taken in a plane at right angles to the plane of Figure 1, as indicated by the line 2-2 of Figure 1. 1

Figure 3 is a longitudinal cross section in a plane identified by line 3-3, Figure 1, i H

Figure 4 is a longitudinal axial section corresponding to Figure 1 but showing the fuze armed,

Figure is a cross section, taken in a plane identified by the line 55, Figure 4,

Figure 6 is a detail cross sectional view as indicated by the line 5-45 of Figure 4,

Figure '7 is a perspective view of the safety lock,

Figure 3 is a perspective view of the fuze rotor, and

Figure 9 is a perspective view of the auxiliary detonator cup.

Referring in detail to the drawing, the numeral I identifies the projectile casing of any desired caliber having a standard base construction, not shown, and its forward end shaped and externally threaded as at Ia, Figures 1 and 4.

A shaped charge 2 having its cavity in the form of a forwardly-directed cone, is secured within the casing I by a thin metal liner 3 which has a forward cylindrical extension 3a secured to the casing as by crimping at 3b into an internal circumferential channel in the casing. It will be understood that the cavity in charge 2 merges into a central axial passageway extending through the charge to the rear end or base thereof. A booster pellet, not shown, which may be of tetryl, is located at the rear end of the aforesaid passageway in position to be initiated by a flame jet passing rearwardly along the passageway and in turn, to detonate the charge 2 at the rear end thereof. It will be understood that the aforementioned axial passageway is lined the same as the conical cavity of the charge. Such lining may be an integral continuation of lining 3, or it may be initially formed separately from 3 and interfitted therewith at the meeting ends to form an imperforate continuous passageway or flash tube to the base of the charge.

A fuze body generally identified by the numeral 4, is shown as a one-piece item preferably formed as a die casting of thin-walled aluminum alloy. This body comprises a main cylindrical section 4a internally threaded for attachment with threads Ia of the projectile casing. A central coupling 41) extends rearwardly from the transverse wall 40 for engaging and supporting a first or auxiliary detonator 5, subsequently described.

A protuberance id extends from the forward face of wall 40. This protuberance is generally rectangular in plan, as clearly shown upon Figure 3, and has a central bore 6 extending in the direction of the maximum dimension of the protuberance transverse to the longitudinal axis of the projectile. An axial tubular projection or neclc portion 46 extends forwardly from protuberance 4d and has a central bore I opening into the bore 6 and through the forward end of the neck portion. The forward end of bore 5 is counterbored to form a shoulder or seat for a sensitive pinless or impact primer 8 secured in position on its seat by crimping as at 9, Figures 1 and 2. A hollow ogival nose or windshield I0 of thin metal is secured to main section la of the body, as by crimping into a circumferential groove in the body as indicated at I I, Figures 1, 2 and 4. From Figure 1 it will be noted that the primer 8 is positioned closely adjacent to nose of the windshield where it is detonated substantially instantaneously on impact. Because it is not required to support any of the fuze elements, and also because the extremely rapid action of the fuze does not require any retardation on impact, the nose cap or windshield I0 may be made of thin light metal. It therefore disintegrates rapidly and completely on impact and offers little or no obstruction to the penetrating action of the ensuing jet from charge 2.

Means are provided to render the fuze safe in handling and to arm the same only in response to centrifugal force engendered by rotation of the projectile effected by firing. These means comprise a rotor I2 having a cylindrical portion 52a (Figure 8) smoothly fitting bore 6, and an integral flattened end portion I2b symmetrical in an axial plane (the plane of the paper in Figure 5) through the rotor axis, which axis is coincident with that of bore 6. Rotor I2 has a diametrical bore I3 adjacent one end, in which a second detonator I4 is fixed as by staking or crimping. From Figures 5 and 8 it will be noted that the axis of bore I3 is normal to the aforesaid axial plane and to the flattened parallel faces of portion $21). A pair of locking sockets I5 and it are formed in the flat end of the rotor. In its unarmed position, the rotor I2 has a rotational position within bore 6 in which the aforesaid axial plane is at 45 to the longitudinal axis of bore 1. In this position the ends of bore I3 are out of alignment with bore 1, and are, in fact, completely closed by the walls of bore 6, as clearly shown at Figure 2, so that communication between primer 8 and auxiliary detonator 5, is cut off and the second detonator I4 is itself then completely enclosed within bore 6 and out of detonating relation with primer 8.

The rotor I2 is locked in the aforementioned safe position by a lock element consisting of a cup or locking element I! having a fiat base. A pair of prongs or lugs Ila and HD extend outwardly from the base and are spaced to enter sockets I5 and I6, respectively, when the elements I2 and I? are in the safe position. Cup H has a pair of diametrically opposite slots I10 and lid in its side walls. These slots, as clearly shown upon Figure '7 for slot I'Ic, extend in an axial direction from the rim, a distance somewhat less than half the axial dimension of the cup. As indicated in Figures 5 and '7, the rim of the cup may be channeled as at I8, for staking, as subsequently explained.

A pin I9 is mounted in holes in body 4, diametrically aligned across bore 6 at the outer end thereof. This pin is inserted through the forward hole and passes through slots I10 and [1:1 to limit the outward movement of cup I! in bore 6. The pin may be locked in position by staking or peening.

A spring abutment cap 20 is axially slidable within cup I1 and, prior to assembly of the complete fuze, is held within the cup by staking the channeled rim thereof as indicated at 2!, Figure 6. However, when assembly is completed, pin I9 acts as an abutment for cap 28. A spring 22 acts between cap 20 and the base of cup I! to urge the latter into engagement with rotor I2 with lugs Na and i129 engaging within sockets or holes I5 and is. Since cup- I! is positively prevented. from rotating by pin I9, and is urged toward the closed end of bore 6, that is, down wardly as the parts are shown upon Figure 1, the fuze is effectively maintained in unarmed condition. No shock or jar tending to move rotor i2 axially along bore 6 can arm the fuse since any resulting movement will move detonator I4 upwardly in Figure 1 out of the axial planeof bore 1 normal to the plane of the paper of this figure. Furthermore, since rotor I2 has a greater mass than cup I'l, any such shock willmerely tend to force these two elements into closer contact. Therefore, rotor 121s continuously locked in the safe or unarmed rotational position of Figure 1, until the projectile is fired. Detonator I4 is secured in position within the bore l3 in any suitable manner, as by staking or crimping. Friction between rotor l2' and the closed end of bore 6 is reduced by the tapered end of portion I21).

Auxiliary detonator has been previously mentioned. Referring particularly to Figure 1, this item consists of a cylindrical holder to which may be of the same light alloy as is used in the construction of body 4. The body has a thin'partition at the base of coupling 4b, centrally perforated to form a continuation of bore 1. The one-piece cup 5b of the detonator has a conical depression in its closed rearward end and a flanged forward end. When holder 5a; is screwed into the coupling 4b, it acts through flange 50 to clamp the dstonator cup in position against an interposed imperforate thin disc 23 which may be of onignskin paper and acts to seal off the explosive within the cup.

The operation willbe clear from the foregoing description. Figures 1' and 2 show the fuze unarmed with rotor 12 in position such that bore 1 is closed to cut off all communication between primer 8 and auxiliary detonator 5 and with detonator l4 sealed within bore 5. Ast he projectile reaches a rotational speed of more than 1500 R. P. M. but less than 3000 R. P. M. as it traverses the rifled bore of the gun in firing, the centrifugal force first causes ,cup 11 to move outwardly along bore 6 to the position shown at Figures ,4 and 5, thusfreeing the rotor .12. The center of gravity of rotor I 2 is located between the longitudinal axis of the projectile, that is, its axis of rotation, and the closed end of bore 6. Consequently, the resulting centrifugal force on the rotor acts to urge it toward this closed end. In the unarmed position the plane faces of portion [2b are at about 45,to the axis of rotation, as will be noted from comparison of Figures 2 and 8. Hence when the rotor is freed by lock element I1, it rotates about the axis of bore 6 so that these faces lie in planes normal to the axis of spin of the projectile. This is the position shown upon Figures 4 and 5, wherein the rotor is nose cap ['0 which disintegrates on impact and offers minimum obstruction to the jet. hil'iew'ise,

the thin-walled and light weight fuze body 4' the projectile as'the latteremerges from the turned counterclockwise from the position of- 5;,

Figure 2, and detonator I4 is aligned with bore 1. The fuze is then fully armed and, on impact, Windshield l0 disintegrates, primer 8 is initiated and, in turn, initiates detonators It and 5. Due to the shaped charged effect produced by initiation of detonator 5, a rearwardly-directed flame jet is produced which extends down the central axial passageway and initiates the previouslymentioned booster pellet, not shown, at the base of the charge 2 to thereby detonate the latter. Because of the novel arrangement and disposition of parts as shown, together with the absence of an inertia-operated firing pin, firing is practically instantaneous on impact and the shaped charge is detonated at the optimum stand-ofi distance from the target where the ensuing jet has maximum penetration. Furthermore, the one-piece auxiliary detonator 5 with its one-piece cup, acts on the shaped charge principle to produce a jet which is sufficient to initiate a tetryl booster at the base of the charge, instead of the more sensitive lead azide, formerly required. The exceedingly rapid and reliable action of the fuze, together with the fact that primer 8 is carried by the fuze body, enable the use of a thin light barrelin firing. The term normal position" in the claims means the position of the partswhii the fuse is without motion of translation or rotation.

Having now fully disclosed our invention, what we is:

1. In a point-initiating fuze for a projectile having a casing and a shaped 'charge therein provided with 'a lined axial passageway tdthe base of the charge, a one-piece fuze 'body"'of brittle, disintegrativ'e metal comprising acentrally-apertured transverse wall and means for attaching said wall'to and across the forward end ofthe casing, a first detonator' secur -ate the rear face of said wall in alignment with the aperture therein and adapted when'initiated;'to direct a jet rearwardly'through' the pas ageway in said charge, means rigidly carried by the forward face cream wa1l"t'c} form a forwardlyextendihg axial passage in alignment'with said aperture, saidbody having 'a"'tr'ansverse" bore interposed between and opening into said aperture and passage, a rotor fitting said bore and rotatable about the axis thereof from a first position in which said rotor cuts off said passage from said aperture, to a second position in which a transverse opening therein connects said passage and aperture, a lock element in said bore and movable outwardly away from engagement with said rotor in response to spin of said fuze about its longitudinal axis, means preventing rotation of said element in said bore, yielding means urging said element into contact with said rotor, interengaging means carried by said rotor and element and operable to lock said rotor in first position only when said element is in engagement with said rotor, and a pinless primer carried by said body at the forward end of said passage, said rotor rotating to second position in response to centrifugal force, when unlocked.

2. In a fuze for projectiles, a fuze body having a central axial flame passage therethrough and a transverse bore intersecting said passage, said bore being open at one end and closed at the other end, a rotor in the closed end of said bore and turnable therein from a first position cutting off said passage, to a second position in which a hole through said rotor is aligned with said passage, a locking cup fitting said bore at the open end thereof, said cup having diametrically opposite slots in its wall, a pin fixed in said body and extending through said slots to prevent rotation of said cup and to limit movement thereof along said bore from a first position engaging said rotor to a second radially outward position out of contact with said rotor, interengaging means between said rotor and cup holding said rotor in its said first position when said cup is in its said first position, and spring means yieldingly urging said cup into contact with said rotor.

claim and desire to secure by Letters Patent 3. In a fuze for a gzru ectile WlLlGh rotates about a longitudinal axis in flight, a fuze body having a central passageway coincident with said axis and a transverse diametral bore intersecting said passageway between the ends thereof, said bore having one end closed, a rotor rotatably and slidably fitting said bore said rotor having its center of gravity radially offset from said longi-' tudinal axis when in contact with the closed end of said bore, said rotor being constructed and arranged to rotate about the axis of said bore under centrifugal force due to rotation of the fuze about said longitudinal axis, from a safe position wherein a transverse hole therein is out of alignment with said passageway, to an armed position wherein said hole is aligned with said passageway, a pin secured in said body and extending across said bore at the end remote from said closed end, a locking element slidable in said bore between said pin and rotor and having slots embracing said pin whereby said element is restrained against rotation in said bore, a spring interposed between said pin and said element whereby the latter is urged into contact with said rotor, said rotor and element having means interengaging only when said rotor and element are in contact, and said rotor is in safe position of rotation, the centers of gravity of said element and rotor being on op osite sides of said longitudinal axis when said parts are in normal position.

4. In a fuze for a rotating projectile, a fuze body having a central longitudinal axis of rotation and a central flash passageway coincident with said axis, there being a transverse diametral bore in said body intersecting said passageway between the ends thereof and having one end 8 closed, a rotor fitting said bore for axial movement and for rotation therein about the axis of said bore from a safe position closing said passageway, to an armed position wherein a diametrai hole in said rotor is aligned with said passageway, said rotor being so proportioned as to rotate from safe to armed position in response to rotation of said body about said longitudinal axis and having its center of gravity radially offset from said longitudinal axis in the direction of the closed end of said bore, a locking member slidably fitting said bore and having its center of gravity upon the other side of said longitudinalaxis of the projectile from said rotor, means limiting said member to axial translation only in and along said bore, means yieldingly urging said member along said bore into contact with said rotor, and detent means between said rotor and member and interengaging only when said rotor and member are in contact and said rotor is in safe position.

ALFRED F. TEITSCHEID.

DONALD R. BEEMAN.

HYMAN D. RUTKOVSKY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,792,631 Deevy Feb. 17, 1931 2,392,884 Semple Jan. 15, 1946 FOREIGN PATENTS Number Country Date 577,531 Great Britain May 22, 1946 614,320 Great Britain Dec. 14, 1948 606,474 Great Britain Aug. 13, 1948 

